1. Field of the Invention
The present invention generally relates to an internal signal test device and a method thereof, and more specifically, to a technology of testing a cycle of an internal signal by distinguishing a high level period and a low level period of the internal signal, at a wafer and package state by using an external test equipment.
2. Description of the Prior Art
Generally, a semiconductor memory device outputs an internal signal such as a refresh signal. Here, since the cycle of the internal signal is easily varied depending on changes of a process and a temperature, the cycle of the internal signal is required to be tested in order to sense the changes.
However, there are no methods for testing an internal signal at a wafer or package state. In the prior art, the internal signal is observed by naked eyes in oscilloscope using a pico probe.
The observation by naked eyes is not precise, and although changes in the cycle of other internal signals depending on changes of the process and the temperature are sensed, economical and temporal consumption becomes larger to compensate the changes.